Photometric analyzer



Sept 30, 1952 E. c. MlLLER 2,612,698

PHOTOMETRIC ANALYZER y Filed March 6, 1950 2 SHEETS- SHEET 1 AoRA/Eys A Sept' 30, 1952 E. c. MILLER 2,612,608

PHOTOMETRIC ANALYZER Filed March 6, 1950 2 SHEETS- SHEET 2 INVENTOR.

E C. MILLER l F IG. 3. ATTORNEYS Patented Sept. 30, v1952 UNITED ASTATES.lag'rslvr OFFICE r2,612,608 y PHo'roMETRIo ANALYZER Elmer C. Miller, Bartlesville, Okla., assignor to Phillips Petroleum Company, a corporation of Delaware Application March 6, 1950, Serial N0. 147,979

lyzer in which one stream is analyzed to determine the proportions of a plurality of components therein.

Heretofore, analyzers have been proposed in which `a beam of radiation passes between 'a source Vand a radiation detector, arrangements being provided for successively interposing 'various samples of fluids to be analyzed between the radiation source and detector, the resultant changes in the radiation incident upon the detector being representative of the composition of thejsample., Thus, where the analyzer is to function with a plurality of sampling devices, it is necessary. that different sample cells be successivelypassed between the sourceA and detector. In order to obtain proper optical conditions, precise-alignment of the sample cell with respect to the radiation detector is required, and this is quite diiiicult to obtain with'a mechanical device for successively'movingv different cells between'the source and detector. It is also known in the art to provide two radiation beams which are directed upon separate detector units, one of these beams passing through a standard cell containing a pure component which is to be analyzed for, and the sample itself flowing through the othercell which is interposed between the` second radiation source and detector. Electrical comparison of the detector outputs, as by a Wheatstone bridge circuit, produces an unbalance voltage which is a measure of the percentage of the desired component in the sample.

It is customary in such devices to provide other cells in 'each optical path. For example, interference cells may be vprovided to remove unwanted frequencies from the radiation incident upon the detectors and filters of various types may be inserted in thefoptical pathto perform the same function. Heretofore, s uch analyzers have not been adapted for analyzing a plurality of different streams in a recurrent manner nor for determining percentage of several different components yin aV sample stream, as in a refinery, without the provision of complicated mechanical devices for providing accurate alignment Aof the parts in each of several positions'.

17 Claims. (Cl. Z50-43.5)

It is an object of this invention to Lprovide an analyzer which is suitable for measuring a plu-v rality of streams' or determining the percentages of different components in a single stream without the necessity for providing precise optical alignment as a number of sample cells are successively moved into `alignment with an optical system.

It is a further object to provide such an analyzer which is suitable for use in diversified applications of process indication and control.

It is a stillfurther object to provide such ap"-l paratus constructed in a durable manner with a minimum number of moving parts and having a high degree of reliability.

Various other objects, advantages andfeatures of the invention will become apparent from thel following detailed description taken in conjunction with the accompanying drawings, in which:

` Figure l is a vertical, sectional view, partially in elevation, of the apparatus of this invention. Figures 2 and` 3 are, respectively, sectional views taken ralong the lines 2-2 and 3-'-3 of' Figure 1.

Figure 4 is a schematic view illustrating a modification of the invention; and

Figure 5 is aschematic circuit diagram of an electrical circuit associated withthe analyzer.

Referring now tothe drawings in detail and particularly to Figures 1 and 2, the apparatus includes a pair of spaced, generally circular supports or decks I0, II which are interconnected by rods I2, I3 and I4, these rods extendingthrough the deck I0 to a base I5 which supports the Whole assembly in an upright position. The rods I2, I3 and I4 also support a deck I6, Figure 2, which, in turn, is rigidly secured to a plurality of cell assemblies I1, as by screws I8. The lower end of each assembly I'I'is rigidly attached to a deck I9 by screws 20 andthe deck I9, in turn, is supported by the rods I2, I3 and I4. Each assembly I1 is composed of a plurality yof arcuate cell supports 2I which extend between decks I6, I9 and are secured thereto by the screws I8 andv 20. Each cell support 2| consists of an elongated channel or track of generally` semicircular cross section and each such cell support is adapted to receive a plurality of cells, generally indicated by reference Anumeral 22, which will be described in more detail hereinafter.

The deck I5 has a metal base member 24 selcured to the central region thereof, as byscrews 25, and the member 24, in turn,l carries a radiation source 26V. In the present example, infra-red radiation is utilizedand, accordingly,

3 the radiation source may consist of a coil 21 of resistance wire having one end thereof connected to ground at 28 through the member 24 and having its other end connected to an insulated binding post 29 secured to the member 24. The type of radiation source will, of course, vary with the type of radiation utilized in the analyses. For example, an .ultraviolet lamp, an incandescent lamp,or any other Isuitablev type of :radiation source may be substituted for the coil 21 depending upon the wave length of radiation desired.

The radiation produced by coil 21 is reected by concave mirrors 29a to 29j, inclusive, arranged in circular formation at the undersider of deck each mirror 29 being supportedfrom an inclined portion 3D of the deck by adjusting screws 3|. The radiation beams reilected by the mirrors 29 pass in parallel paths through a shutter assembly 32 and a trimmer assembly 33'- to the respective cell units 22.

The shutter assembly 3'2 includes a shutter 34 of opaque material rotatably mounted upon va pin 35protruding downwardly from deck The shutter consistsiofa thin circular sheet of metal having two diametrically opposite openings 39 formed therein which are adapted to register, respectively, with the radiation beams incident upon and reflected from two diametrically `oppositevmirrors 29. The central part of the shutter abuts one endof a sleeve 31 rotatably mounted upon pin 35 and is forced into engagement therewith by a collar 38. The other end of sleeve 31 bears against a cam 35i-which isseparated by a collar 40 froma gear 4| also rotatably mounted upon the pin 35. Gear 4| meshes with a gear 42 which, in turn, is coupled through gearing 43 to amotor 44. r

When gear 4| is driven through gears 42, 43 by motor 44,7thel cam 39, sleeve 31, and shutter 34 all rotate as a unit.- The cam 39 is engageable by aroller 46 forming a part-of a snap action switch unit 41. Thevmotor and switch are connected in an electricalcircuitin the manner shown by Figure 5, from which it will be noted that-switch41 is connected in parallel with the contacts 48 of arelay-49these parallel connected switches being connected in series with a current source 50 and the motor 44. The energizing circuit ofrelay 49 is connected in circuit with a timer I -and a battery or other current source 52.` When rollerllt` is positioned within a notch of cam 39, switch 41 is open. The switch 48 is normally open andv is closed whenever relay 49 is energized. Accordingly, uponperiodic actuation of the timer 5|, thelrelay 49 is periodically energized and, at each energization,.the contacts 48 are momentarily closed. This yinitiates rota'- tion of. motor 44 and causes roller 46 tomove out of a notch of cam 39 with the result that switch 41 is closed and remains closed until the roller 46'reaches the next succeeding notch of cam 39. In the position of the parts yshown in Figure 3, the openings 36 are positioned adjacent mirrors 29h, 29e. When timer 5l is energized, the motor 44 moves the 'shutter in a. clockwise direction, Figure 3, until the openings 36 are positioned adjacent mirrors 29o, 291. Thereupon, the roller is positioned within a notch of cam 39 and the motoristops in this'position until the next succeeding energization of timer 5|. The next actuation ofth'e'timer moves the'shutter '34 until the openings 36 are positioned adjacent mirrors 29a, 29d. It will be apparent, therefcirathat` the described recurrentoperation of timer 5| causes the openings 36in the shutter tobe positioned suc- 4 cessively adjacent the mirror sets 29e and '2919, 29e and 29j, and 29a and 29d. This action causes successive actuation of the analyzer units in the manner hereinafter described.

The trimmer assembly 33 includes three units 54a, 54h, and 54o each unit including a mounting bracket 55 secured to deck I6, as by a bolt 56, andyeach brackethavingltwo rotatable pins 51, 58 journalledftherein: Each pin is provided with a flat piece 59 of metal which functions as a shutter, the angular position of each shutter being adjustable by a nut 6U. These shutters constitute means for varying the intensity of the radiation beams-passing-from the respective mirrors 29 to the cell units.|1.

The cell units.|-1 may be of varied types of construction. For convenience, I will describe a cell for determining the percentage of isobutane present in a sample stream containing n-butane, isobutane, and propane. Assuming shutter 34 to be positionedV with the shutter openings adjacent mirrors 295 and 29e, a beam of radiation from source 21 is reilectedfrom mirror 29h and, thence, passes successively` through cells 62, 63 and64' which are secured to the-adjacent channel or track "2| by clamps 65. At'the same time, a raliation beam is reflected from mirror 29e' and passes, in a parallel path, successively through cells 66, 61, 68 and 69 which are secured tothe adjacent channell or track 2|A by clamps 10. The stream to be" tested passes through an inletfHof cell 62, thence through outlet 12 and a conduitkjnot shown, to an inlet 1 l2111. of cell 66, and finally vthan outlet`13. Cells61, 68and69 are lledwith`pure samples of nbutane1,fisobutane and propane. Accordingly, the. radiation, passing through fcells 66 to 69, inclusive, does'notcontain radiation ci the frequencies .absorbed by the ,three cOmDQ i nents of int'erestimthe testsample. That is, the

radiation passinggthroughthis cell'system is irlsensitive to'chan'ges in concentration of n-butane. isobutane or propane in the test sample passing through cell 6.6, although it is influencedby changes in temperaturadensity andconcent'ra'- tion of other components inthe test sample to the same extentas.thebeampassing through cell 62. Thus, the, beam. leaving cell 69 serves 'as a standard or ref ere'ncel against, which' the radiation intensity varying inaccordance with changes of a selected component'rn'ay be realycompared.'

At this point, it shouidbe ncted'that 'the-ends of each cell are provided with` radiationtransparent windows so that-the beams canpass successively through the .,cells. yIn the.' example shown. 'cell 63 'contains'pure n-butane andfcell 64 ,contains purefpropane. Accordingly, the radiation passing through cells 62, 63 and 64 is in-fl sensitive to changes'v in thefconcentration.offnbutane or propaneinjt e sample ilojwjing through cell 62, since the radiation' of wavelengths corresponding .to theabsorptiori bands of these two substances is absorbed within the cells63and64. The radiation beam passing throughjthese, cells, however, is sensitive to change'sfin:theconcentra,-y

tiori of isobutane.; Thus', When-the Vintensity of the' radiationjbeams is compared, the' dillerence inradiation intensitybetween the-two barsis proportional to the isdbutane ccriterltofl the In order to 'effect the. describedcomplison, the deck in reprenne@ withr` concave-mirrors 15afto'15f corresponding totliemirrorsi29, each mirror being mountedfonvan inclinedy portion` 16 of deck I0 byv bolts .16a. The ,parallel beams from the cell 'unimi/.1 arerreiected from mirrors 15 and enter. a twin radiation detector assembly 11, the. beams from mirrors 15d, 15eand 15f.

being incident upon one detector, and the beams from mirrors 15a, 15b and 15e being incident upon the other detector assembly. In the casev of infra-red radiation, the detectors are bolometers, two such units being provided'fwlthin the assembly 11. These bolometers are connected. inv

a 'Wheatstone bridge circuit well known to those skilled in the art and this bridge circuit is connected to an indicating or recording vdevice which indicates vthe diiierencein intensity of the beams incident upon the twin detector unit and, hence, a quantity proportionall to theconcentration of isobutane in the test sample.

corresponding to that already described is vprovided between the mirrors 29d, 15d on the one hand and mirrors 29a, 15a on the otherhand.

yHowever, the -cells corresponding .to cells i363 and 64 are filled with isobutane and propane rather than n-butane and propane. The radiation incident upon mirror a, therefore, varies 15 In" the present example, a similar cell structureA in intensity in accordance with variation in the ia content of n-butane in the testvsample. Thus,

when the shutter 34 is in such position that the openings 3' are adjacent mirrors 29a and 29d, the detector circuit indicates the concentration of n-butane in the test sample. A similar cell.v

system is provided between the mirrors 29f, 15J

onthe one hand and mirrors 29e, 15o onthev other hand except that the cells corresponding.

s timer 5| is recurrently actuated and the openings 36 in shutter 34 successively move to positions in front of ymirrors 29h and 29e, 29o and 29j, and 29a and 29d, the sample stream is successively analyzed to determinethe proportions of isobutane, propane, and n-butane therein, Hence, a recorder connected to the output ofthe detector circuit will successively record the concentrations of these three components in the sample stream. The trimmer assemblies 54 are initially adjusted to equalize the intensity of the radiation beams passing through `the cells and vneed not be adjusted duringl subsequent operation. Accordingly, the optical system contains no' moving parts and there is no problem of successive alignment such as would be encoun-l tered if the Vcell units were successively moved into positionv mechanically in a single optical system. Moreover, the system is very flexible, since the arrangement of cells traversed by the parallel beams may be readily varied simply'by The radiation incident adding or removing cells from the channels 2|.

However, only one source and one bolometer system is required to record the concentration of three or more components in the test stream.

Since the celll units associated with mirrors 29d and 15d, 29e and 15e, and 23f and 15j, are all of identical construction, it will be evident that only one set of cells need be provided to furnish the standard radiation intensity for comparison purposes. In this manner, the described system could be utilized to record percentages oi five components ina test stream lsincefiive other cell units are then available. Inmodifying the apparatus tosuch an end, the standard cells with their attendant optical system may.' be moved outwardly beyond the -radius of the.

other cells or, alternatively,the mirrorf29e may be positioned below the shutter 34 so that radiation is always vsupplied .to the cells associated.. therewith. In such `a modiiications, .the cam 39 is modied so that the single shutter vopening v required moves .from mirror 29d past 29e to mirror'29f with `the result that theradiation intensity passing through the standardk cell unit is at all times compared `with one of the five other@ units. This may be very readily accomplished*- simply by omitting one notch from thevcam.

It is preferable, however, to utilize three.y identical systems in the manner described in.n

the iirst embodimentof the invention for this increases the flexibility of the apparatus.

64, 61, G8 and 69. stream is fed tothe cells associatedy with the mirrors 29d and 29a; and separate additional'. cells are provided in connection with each of the sample cells, while a third stream may-'be analyzed in the `units associated with mirrors- 29a and 29f. Thus, the apparatus of my-inven'- l tion permits great flexibility and sample cells,-y

interference cells or any desired types of filters may be readily changed as desired by connecting them at approapriateregions of the channel 2 l .Y

It will befurther apparent that each set of cells passes through a'period whenthe recording unit' is not responsive tothe radiation passing therethrough,'the shutter 34 preventing the passage of radiation through the cells during this period.- It will further be obvious that r.the ap'-,E paratus of my invention is not restricted to the.

use of six opticalchannels, it being possible `to use more or less channels as desired.' When four channels are utilized it is possible to simplify the shutter arrangement in the mannershown in Figure 4, wherein reference numeralsV 8|, 82, 83 and 84 represent mirrors corresponding y to the mirrors 23 of Figurel. A small rock shaft is journalled in a bearingv 86 and rthis shaft: carries two shutter plates 81'and 88 which may prevent passage of radiation to mirrors 8l, 82 or 83, 84, as desired. 'The shutters may be moved from one position to the other manually, `as by 'knob 89, orthey may be driven automatically by amotor-timer mechanism in the manner shown in Figure 1. y While the invention has been described in connection with a present, preferred embodimenty thereof, itis to be understood that this description is illustrative only and is not intended to@ limit the invention, the scope of!` which is 'defined by the appended claims.' l I claim:

l. In a photometric analyzer', in combination,r a radiation source, a radiation detector, reflect" ing means to form av plurality of radiation beams extending between said source and said detecter, n

a plurality of cellsdisposed in the path of the respective radiation beams and adapted to hold a substance preferentially absorbing certain Wave lengths of said radiation, and a rotatable shutter of opaque material disposed the patl'iv` of said radiation beams for selectively permitting Thus, i merely by rearranging the sample cells, three l separate streams 'may be successively and recur l rently analyzed-the readingsl appearing upon a f lcommon indicator-tor recorder unit. Thus, one stream is passed 4through cells 62, 65 with ap-V propriate materials being placed in the cells 63, An entirely different sample amarnos@ ioa-ssg"eeofzrselectefkislcamezolrradiatonfbetween@y satdcsounce :and said detector: .whilefpreventingii theipassageof Iotlierf.loeamsfloett/cenfsaidrsourcei4 andssaid Tdetector' 2;:Inzazphotometrc .analyze-1min: combination., 5 1

a radiationsource, .aradiaticinzdetector;reecte ingimeansftoiform; afplliralityofparalleb radiaa tion ibeamstextendin'g'.; ibetweenfsaid:sourceeandrz said frietectorcaipluralty ofticellsidisposed-:inrthes path-:tofs: the frespective z radiation fbea'msiifeachezm;

adapted towhold` :aasubstanceeLpreferentiallyfab. sorbi'ngertalnz wavealeng-ths roffaa'diationg; andrai; motorcdrivenrrotatable :shutteraof ropaque matee y rialdls'posedin the :pa-tirant .said radiationribeamsa.

said shutterzhaving .anropeningtherein for vpere. 15

mittin'g passage .of az-selected beamiofrradiaton therethroughi: v 1" 351m .a photometric'analyzera,inacombinatloma a lra'diationtsourcer a :radiationrzdetecton reilect. A

ingim'e'ans :to formia fpluralltyofaradiation! beams Qu extendingrbetweenrsaidasource andzsaidn detector;A a .=,plurality1-of :cells disposed: irrth'eupathfofvthesAA respective' radiationifbea-msfand adapted tozholdz.n a substance preferentially ;absorbing;certain .wave

lengths:A of radiationi:l af. movable-f shutter: vof: 25

opaque:inmateriall disposed in .the path: of said` raf:

diation beams,said= (shutter thaving 3 an lopemngzf; thereinfor permlttingl passage` of ai selectedr, bea-maori radiationtherethrough," a. motor for`4 driving said shutter; arcamfdriven'. bh-said:anotar;I 30

and ai. camactuatedaswitch t connected inrthe.VI motonfcircuit. toadeenergizesaidtmotor each time f. the shutterfopening is fin/rpositionfto permit. pas-f sage oi onerzof' :saidradiation beamsf 4;. Anl analyzer.constructedfm. accordanceavth- .35 rality igt-amar Supporting-channels.,oneafdr: each claim'i3 fin; which the i radlationisourcef-is -af hea-tado4 lament icapablefof zemitting infra-,red radiation and theradiatiorr detector lis a'rbolometer.-

5.- Afphotornetric analyzercomprising; in combinat-ion, aradiaton ysoui'r:e;.,aradiation. detee-y 40 channel *members each :adaptedfto vholdy aaplu -4 ralfity; of duid-containing cells in., position lto .be traversed by one vof. 'said radiation i-laeams,` and -af movable shutter ofopaque/:material positionedto prevent 'passage of saidaradiation beams,Y said.

therein vto .'permit--passageaof at least one beam., of. radiation l.from the source to, .the detector.- in each `of several` shntterpositions..

6. A- photornetrieanalyzer comprising, in coml bination, aradiation source,a vradiation deteo-4 55 tor,. .ai l.plurality ofv l. mirrors .for .reectingradiation from said source along a plrality,of.parA allel paths, a..plurality of mirrors spaced-from said nist-mentioned .mirrors .for reflecting .said

parallel beams upon saidde'tector, a series off'o channel 'members each` adapted 'to'h'old a plu-n ralitjf of"iiidlcontaininggcells infposition to be:4 traversed by'one 'of said radiatonb'eams'a'mow able shutter of opaquematerial-positionedrto prevent passage of said radiation beams: said 65- shtl'tt'erhaving` at least` onef opening formed th'erein to permit'passage/ofv at least one'beamof radiation" from"the source' to 'thedetector in each'ofseveral shutter-positionsand a series-` oi trimmer 'assemblies' one Y for f each' beam,v each 70- trimmer comprising' an opaque-plate'which' is movable intcvandoutvfof` a' path` of fradiation beam tocontrol the "amount of4 radiationrpassi'- A V ingbetween -theisouree :and the detectorinfsaiazl- V 7.'J'Aphotom'etric analyzeafcomprisinggin come;

binatidnpa -radiatio'n source; aradiatidnaletector,1 a pluralityfof;mirrorsifoicreectingradiation .fromm saidf'sourcegalong fa 'iiluralitS/i" onpa'rallelz paths,-x ai, pluralityiofifmirrors'lspacedfromifsaidirstamenationed emirrorsiforcrelecting :said: iparallelbeams upon said "detector-ya; series? ofI fchannele members.; eachadapte'datorholdfa :plurality-:ofi fluid-contains. ingwellsfin'positionito beftraversedfby :one os'ai'd i radiation ,beams ,axmovable 1shutt'erwof fopaquel material positioned 'to preventrzpassagexof said/iV radiatio'nfbeamsisaidfshutter havingatleastzonee" openingzformedntherein tot-permit Ipassage fof=y ata; least Tone :beam7 off :radiation: .from n.the source ttor.: the detecton':inreach1 of fseverali'shutter positionsff. a motor: fon drivingzsadefshutter,= afcam @driven by fsadfmotoigfa:normally closed-switch? connectedf` iniy the anotan circuit and-:actuatedfby *said' carrrftaf interruptthemotorfcircit atfeachoffsaid-'seventh-3V fshutterr'posit'ions; .andla timer' constructed* and# arrangeda iso-supply a :short zdrv'i'vinglpulse-std saidli' moto'rat-each energizationfthereofaf i'Afphotom'etric analyzer r'comprising; inl'com-4 binatlon,:a spair Aof spacedfgenerally circularsupef tions detector l uniti imauntedA ibetweenf *saidde'ck's aln'g ar-Iinemonn'ectihg the-axesV ofsaid decks-fax plurality'uoffmirrors arranged infclrcular :forma-z. tioneupontonefof -said decks =toreflectradiation-'- from .saidrssonreev inl )paths l.generally f parallehto saidgaxi-al Aline,fa:plu'ralit'Y--of mirrors onfthe otherA decision reflecting-'at least 'one of saidfbeamsl-upon' one .'offsa'rd idetecto'runits-and-` for refiec-tin'gflthee otherlb'eams -uponrthe fother detectorfunit',i ambi'- heamg. at'rle'ast'fone liluidcontainin'g'-- cell: disposed 1mi-each `channel to` permit 'fpassage Lof ,fthe lasso? mated.1radationazbeamtthmugh V.the num-m- :sardi-J cell,y 1 a `ashutter Eof opaqueA material fo'rprevent-ing;i passage roffradiatinhfrom saidfsourcet said iist mirrors, said shutter 1having sani' openingtherein" torpermit passagel` of fradiation from saldi-source tofat Ileast one ot A"sai'df iist-'niirrorsand reflcticinr therearfthmughzsaid 'cei-rs'tefth-e fothewfsaidc tmirrors; and: :meanssfor fmoving said shutter to i severatfdiierent -'positi'ons;=thereby vto 'selectivelyhr permit fpassageiot'selec-ted radiationfbeains from bn'atona pair'ofs ace 'n shutterv having@ at least one opening formed 50 p d ge erauy mmm-ar Sup port' decks; `aL'r'adfaltimrjsourceand af'twin'radia= tion K detectorf-mounted*between saiddecks .along a linie':connecting 'fthe raxesmffsaidz decks; ,a "pirality ot imirrorsarrange'd w-invcir'clar formation* saidlso'urce uinpaths generally,- parallellto said axial line,- afpluralityfof mirrors on the other deck;

iof- 'said detector units andfo'r reecti'ng the other.-.

beams rponfthe other `detector unit; a.plurali'tyl of..

radiation' 'fxrom'said fsource Vto saidjst .mirrors sald shutter'havingaIIQDenigvtherei to permit passage'of radiationromsaid source-,to` at' 'least i one-f-of- Fsai'CV-frst*mirrors* and "rection thereof therebyto move'said'ppeningtosevera l l 'Y l n l different positions-topermit passagefofat least'one selected' radiationbeam'between saidfsource andsai'd-d-r tector; alcamvdnvenrby Jsaid motoria* camal:` 5

tua'ted switch connected in the'rnotor circuit to interrupt same at each of said lseveral positions,

'and a timer for supplyin'gshort pulses of current to said motor to override the opening of said cam- 'operatedv switch yand permit movement of the shutter to the next of said several positions. l

10. A photometric analyzer comprising, in com` bination, a pair of spaced generally circular support decks, a radiation source'and a twin radiation detector mounted between said decks along `a line connecting the axes of said decks, a plurality of mirrors arranged in circular formation upon one of' said decks to reflect radiation from said source in paths generally parallel to said axial line, a plurality of mirrors on the other deck said shutter having an opening therein to permit passage of radiation from said source to -at least one f said first mirrors and reection thereof through said cells to the other vof said mirrors, a motor for driving said shutter, thereby to move said opening to several different positions to permit passage of at least one selected radiation beam between said source and said detector, a cam driven by said motor, a cam-actuated switch connected in the motor circuit to interrupt same at each of said several positions, a timer for supplying short pulses of current to said motor to override the opening of said cam-operated switch and permit movement of the shutter to the next of said several positions, and a trimmer assembly associated with each beam to vary the amount of radiation making up such beam.

l1. A photometric analyzer constructed in accordance with claim 9 in which the radiation source is an incandescent filament capable of emitting infra-red radiation and the twin detector unit is a twin bolometer.

12. A photometric analyzer comprising, in combination, a pair of spaced generally circular support decks, a radiation source and a twin radiation detector mounted between said decks along a line connecting the axes of said decks, an even number of mirrors arranged in circular formation upon one of said decks to reflect radiation from said source in paths generally parallel to said axial line, a plurality of mirrors on the other deck for reiiecting half of said beams upon one of said detector units and for reflecting the other beams upon the other detector unit, a plurality of axial supporting channels, one for each beam, at least one fluid-containing cell disposed in each channel to permit passage of the associated radiation beam through the fluid in said cell, a shutter of opaque material for preventing passage of radiation from said source to said iirst mirrors, said shutter having two diametrically Vopposite openings therein to permit passage of radiation from said source to two diametrically i to the next of said several positions.

'13. A' photometric 'analyzer comprisir'ig,l combination, a pair of spaced'generally circular same at each of said several positions, and a timer for "supplying short pulses'y ofV current -to said motor to override the openingof said cam-operated switch and'permitmovementof the shutter support decks, a radiation source and-i'a-twin radiation detector mounted between saidfdecks along a line connecting the a'xes'i 'saiddecks six mirrors arranged in circular formation upon one oi said decks to reiiect radiation fromsaid 'source in paths generally parallel to'said axialilineiilslx mirrors on the other deck for reilecting three adjacent beams upon one 'of said detector units and for reilecting the three'other beamsfu'pon the other detector unit, a plurality of axialisupporting channels, one foreach-beam, the channels for said three adjacent beams each carrying a sample cellfand cells' containing apure vsample of three components to be analyzed in'said sam-v ple, said cells being disposed in the paths of=the radiation beam, the channels for said three other opposite rst mirrors and reiiection thereof through said cells to the other mirrors, a motor for driving said shutter, thereby to move said openings to several different positions to permit passage of two diametrically opposite radiation beams between said source and said detector, a cam driven by said motor, a cam-actuated switch connected in the motor circuit to interrupt beams each carrying a sample cell and cells 'containing pure'samples of two of said three components, said two components being different in each cell assembly, said cells being disposed VVin the paths'fofthe radiation beams, a shutterl of opaque material for preventing passage of radiation from said source to said iirst mirrors, said shutter having two diametrically opposite openings therein to permit passage of radiation from said source to two diametrically opposite first mirrors and reflection thereof through said cells to the other mirrors, a motor for driving said shutter, thereby to move said openings successively to three diii'erent positions to permit passage of two diametrically opposite radiation beams between said source and said detector at each position, a cam driven by said motor, a cam-actuated switch connected in the motor circuit to interrupt same at each of said several positions, and a timer for supplying short pulses of current to said motor to override the opening of said camoperated switch and permit movement of the shutter to the next of said three positions.

14. A photometric analyzer comprising, in combination, a pair of spaced generally circular support decks, a radiation source and a twin radiation detector mounted between said decks along a line connecting the axes of said decks,

an even number of mirrors arranged in circular formation upon one of said decks to reiiect radiation from said source in paths generally parallel to said axial line, a plurality of mirrors on the other deck for reiiecting half of said beams upon one of said detector units and for reflecting the other beams upon the other detector unit, a plurality of axial supporting channels, one for each beam, a cell assembly for each beam disposed in the respective supporting channels, the cell assemblies associated with the first half of said beams each including a sample cell and a cell for selectively absorbing energy of certainy wave` lengths in the beam, the cell assemblies associated with the other beams each including a sarnple cell, a shutter of opaque material for preventing passage of radiation from said source to said first mirrors, said shutter has diametrically opposed openings therein to permit passage of radiation from said source to two diametrically opposite iirst mirrors and reflection thereof through said cells to the other of said mirrors, a motor fordriving said shutter, thereby to move said opening to several different positions to per- 

